1. Technical Field
The present invention relates to a flotation device for the removal of dispersed particles in a fluid, in particular removal of dispersed oil in water.
2. Description of the Related Art
When producing oil and gas from geological formations beneath the sea bed and the ground, considerable quantities of water may also be produced. In professional circles this is called “produced water”. Apart from dispersed oil, this water also contains various types of dissolved hydrocarbon in addition to dissolved metals and other chemical substances. Produced water is generally dumped, i.e., in connection with offshore production of oil and gas, discharged into the sea.
Regarding the content of dispersed oil in dumped water, the authorities in the various countries have set discharge requirements that must be met by the oil companies producing oil and gas. In the Norwegian sector of the North Sea and the Norwegian Sea, this requirement is currently 30 ppm oil for produced water. Future requirements are, however, expected to be lower than 30 ppm.
There are currently no specific discharge requirements for dissolved hydrocarbons (HC), but statements by the authorities indicate background level discharge requirements.
Existing technology for the removal of dispersed hydrocarbons from produced water normally includes a first step gravitational separator, a flocculation tank and a first step hydro cyclone, a second step separator, a second step hydro cyclone and a degassing tank. Such known equipment is very, comprehensive with many components and is both expensive to manufacture and operate.